This invention pertains to the field of prosthetics, and more particularly, to an inflatable/deflatable, partially leg-encircling, patellar cushioning support device usable with a below-the-knee prosthesis.
For below-the-knee amputees who are fitted with a prosthesis, there are several important matters to consider regarding the manner in which the stump fits and is supported within the upper open end (cavity) of the prosthesis. One consideration, of course, is that with the prosthesis in a weight-bearing condition, adequate fore, rear and lateral support must be provided. Another is that such a prosthesis should be capable of providing this kind of support without producing undesirable and uncomfortable local bone pressure, and also without creating vascular or nerve-system constriction.
In the past, prosthetic devices have been proposed which include inflatable collars that seat within the upper end of a prosthesis of the type generally described--for the purpose of providing cushioning for a stump received in the prosthesis. However, these devices usually have not been capable of providing adequate weight-bearing support, while at the same time minimizing the problem of constricting vascular and nervous systems. One reason that prior-known inflatable supports, such as the kind just generally mentioned, have not worked satisfactorily, is that they completely encircle a stump, and when inflated sufficiently to provide adequate support, close so tightly upon the stump that they create undesired constriction.
A general object of the present invention is to provide a unique inflatable/deflatable air bag designed for free insertion and use within the upper open end of a below-the-knee prosthesis, which bag functions, with proper inflation, both to provide adequate standing cushioned support for a user, and to minimize the likelihood of constriction problems, such as those mentioned above.
According to a preferred embodiment of the invention, an inflatable/deflatable air bag, having what might be thought of as a butterfly-shaped perimetral outline, is proposed for fitment in the upper front portion of a below-the-knee prosthesis.
It is typical in such a prosthesis to have an upper rim which is non-uniform in height, and which, in particular, has a valley at the front side, and, rising therefrom, as one progresses toward the rear of the prosthesis, upwardly extending lateral support hills.
The air bag of the invention is shaped in such a manner that, when it is fitted in place, its upper margin generally follows the front and lateral rim portions of a prosthesis. The bag of the invention does not extend completely around the upper part of the prosthesis.
Extending from the bag is a flexible tube joined at its upper end, through a quick-disconnect, releasably lockable coupling, with a conventional hand pump that can be used selectively to inflate and deflate the bag the amount desired.
What might be thought of as the "wings" in the butterfly shape of the bag, have opposite extremeties each formed with an inwardly extending dip. These dips, with the bag in place, prevent the bag, when inflated, and when in use, from exerting excessive pressure in lateral knee-joint regions which are particularly sensitive to vascular and nervous constriction. Because of these dips, and because of the fact that the bag extends only partially around a stump received in a prosthesis, undesirable constriction is substantially completely eliminated.
The bag proposed by the invention is extremely simple and reliable in construction, and can be made in a variety of sizes to suit different circumstances. It is freely placeable in and removable from a prosthesis at the choice of the user.
These and other objects and advantages which are attained by the invention will become more fully apparent as the description which now follows is read in conjunction with the accompanying drawings.